Drug interactions
methotrexate + trimethoprim-sulfamethoxazole
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Overview
Severe myelosuppression/mucositis.
Mechanism of action
Additive antifolate effects.
Clinical management
Avoid; if used, monitor counts and consider leucovorin rescue.
Drug reference
References
Frequently asked questions
Can I take methotrexate with trimethoprim-sulfamethoxazole?
The interaction is rated: Major. Severe myelosuppression/mucositis.
How serious is the interaction between methotrexate and trimethoprim-sulfamethoxazole?
The interaction is rated: Major. Evidence level: High.
How is the interaction between methotrexate and trimethoprim-sulfamethoxazole managed?
Avoid; if used, monitor counts and consider leucovorin rescue.
Why do methotrexate and trimethoprim-sulfamethoxazole interact?
Additive antifolate effects.
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